1. Field of the Invention
The present invention relates to a plasma welding torch that performs plasma arc welding on a base material and a welding method using the plasma welding torch, and more particularly relates to a plasma welding torch that can be made in a size smaller than in conventional cases, and a welding method using the plasma welding torch.
2. Related Art
Conventionally, there is known a technology of welding a base material using a plasma arc formed between a non-consumable electrode and the base material (For example, see Japanese Unexamined Patent Application Publication No. 2008-238242). Such welding is generally referred to as “plasma arc welding”.
In plasma arc welding, a plasma welding torch that contains a non-consumable electrode is employed.
A conventional plasma welding torch is supplied with plasma gas together with shielding gas in order to form a plasma arc between the non-consumable electrode and the base material. By ejecting such shielding gas from the conventional plasma welding torch, the molten weld pool that is formed on the base material is prevented from oxidation and, as a result, the quality of welding is maintained.
For this purpose, a conventional plasma welding torch is provided with a nozzle for plasma gas and a nozzle for shielding gas in such a manner that the nozzle for plasma gas surrounds the non-consumable electrode and the nozzle for shielding gas surrounds the nozzle for plasma gas. This means that the conventional plasma welding torch has a dual nozzle structure.